1. Field of the Invention
The present invention relates to an opening-sealing apparatus for a honeycomb molded body, an opening-sealing apparatus for a honeycomb fired body, a method of filling a plug material paste, and a method of manufacturing a honeycomb structured body.
2. Discussion of the Background
In recent years, particulates such as soot and the like contained in exhaust gases discharged from internal combustion engines of vehicles, such as buses and trucks, and construction machines, have raised serious problems as those particulates are harmful to the environment and the human body.
There have been proposed various honeycomb filters using a honeycomb structured body comprised of porous ceramics, which serve as filters capable of capturing particulates in exhaust gases to purify the exhaust gases.
FIG. 1 is a perspective view that schematically shows one example of such honeycomb filters; FIG. 2A is a perspective view that schematically shows a honeycomb fired body that constitutes the honeycomb filter; and FIG. 2B is a cross-sectional view taken along line A-A of FIG. 2A.
In a honeycomb filter 130, a plurality of honeycomb fired bodies 140 as shown in FIGS. 2A and 2B are bonded to one another by interposing sealing material layers (adhesive layers) 131 to form a ceramic block 133, and a sealing material layer (coat layer) 132 is formed on the periphery of this ceramic block 133.
Moreover, as shown in FIGS. 2A and 2B, the honeycomb fired body 140 has a structure in which a number of cells 141 are placed in parallel with one another in the longitudinal direction and a cell wall 143 interposed between the cells 141 is allowed to function as a filter.
In other words, as shown in FIG. 2B, each of the cells 141, formed in the honeycomb fired body 140, is sealed by an opening-sealing material layer 142 at either one end of its exhaust gas-inlet or exhaust gas-outlet sides so that exhaust gases that flow into one of cells 141 are discharged from another cell 141 after surely passing through a cell wall 143 interposed between cells 141, and accordingly, when exhaust gases pass through the cell wall 143, particulates are captured by the cell wall 143 portion so that the exhaust gases are purified.
Conventionally, in order to manufacture a honeycomb filter 130 of this type, first, for example, ceramic powder, a binder, a dispersant solution and the like are mixed to prepare a wet mixture. This mixture is then continuously extrusion-molded through a die, and the extruded molded body is cut into a predetermined length to manufacture a pillar-shaped honeycomb molded body.
Then, end portions of this honeycomb molded body are sealed, in a checkered pattern, with a plug material paste mainly comprising the above-mentioned ceramic particles, and the resulting product is subjected to degreasing and firing processes to manufacture a honeycomb fired body 140 (see FIGS. 2A and 2B). With respect to the method of filling the cells of the honeycomb molded body with the plug material paste, for example, methods disclosed in JP-A2000-190312, JP-A2001-1332, and JP-A2001-1326 may be used.
Thereafter, a sealing material paste is applied to side faces of the honeycomb fired bodies and the honeycomb fired bodies are bonded to one another by an adhesive to manufacture an aggregated body of honeycomb fired bodies in which a number of the honeycomb fired bodies are bonded to one another by interposing a sealing material layer (adhesive layer). Next, the resulting aggregated body of the honeycomb fired bodies is cut and machined into a predetermined shape such as a cylindrical shape and a cylindroid shape by using a cutting machine and the like to form a ceramic block, and lastly, a sealing material paste is applied to the periphery of the ceramic block to form a sealing material layer (coat layer), thereby completing the manufacturing process of a honeycomb filter.
With respect to a method of filling predetermined cells of the honeycomb molded body with the plug material paste in a manufacturing method of this type, for example, a method disclosed in JP-A 2003-285313 may be used, in addition to the above-mentioned method. JP-A 2003-285313 has disclosed a method of filling cells with a plug material paste in which: a reference cell having a different opening shape is preliminarily formed in a honeycomb molded body and the image of the end face of the honeycomb molded body is picked up to specify the position of the cell opening based upon the reference cell, and a plug material paste is filled in through an opening-sealing mask.
The contents of JP-A 2000-190312, JP-A 2001-1332, JP-A 2001-1326 and JP-A 2003-285313 are incorporated herein by reference in their entirety.